The candidate holds M.D. and Ph.D. degrees from New York University. His long-term career goals are focussed on academic medicine, involving basic neuroscience research. His background in medicine has motivated him to work on the neurobiology of an important disease, such as drug addiction. The mentoring of young scientists and some didactic teaching are also in his career plans. He is currently a Research Assistant Professor in the Department of Psychiatry at New York University Medical Center. The goals for the proposed K01 Award are to gain additional skills in molecular biology and behavioral science to complement a strong background in neuropharmacology and clinical medicine. These additional skills will greatly enhance the candidate's ability to do independent research. New York University Medical Center and the laboratories of Drs. Salzer, Devi, Carr, and Simon provide the finest intellectual environment for the candidate to obtain further training and develop and implement a successful plan for opioid research. Chronic opiate use produces tolerance and dependence. Biochemical and cellular adaptive changes in neural tissue seem to be important contributors. The goal of the research to be carried out during the Award period is to study the mechanism of ligand-induced receptor regulation, with emphasis on down-regulation, as a means of understanding the consequences of prolonged opioid exposure. He is particularly interested in continuing and extending his previous studies on the role of protein kinase C (PKC) in this process. He will examine whether a number of clinically relevant opioid agonists are capable of inducing PKC translocation, and relate this activity to their potential to produce receptor desensitization and down-regulation (specific aim number 1). He will determine if the rapid internalization of opioid receptors into clathrin-coated endosomes is a prerequisite for down-regulation to occur by using cells that express a dominant-negative mutant form of dynamin (aim number 2). The role of PKC isozymes in opioid receptor regulation will be probed by creating cells deficient in specific PKC isoforms using site-directed mutagenesis and anti-sense oligodeoxynucleotides against PKC isozyme mRNA (aim number 3). Finally, in specific aim 4, the possibility will be examined that PKC activity is changed in the brain of rats as a result of prolonged exposure to levels of opioids sufficient to produce significant behavioral changes (analgesic tolerance and locomotor sensitization). The proposed studies should contribute to our understanding of the mechanisms underlying opioid tolerance and possibly, dependence.